Rapid resolution of nucleotide sugars by lectin affinity high-performance liquid chromatography

High-performance lectin affinity chromatography

Lectin high-performance liquid chromatography techniques have contributed to the growing interest in glycoproteomics. Affinity chromatography is a very effective method to separate and purify trace amount of biological substances. In this chapter, we describe a basic procedure for separation of glycoproteins using commercially available lectin-HPLC columns. As an example, α-fetoprotein, known as a biomarker of liver cancer, can be separated at the level of their glyco-isomers by using a Lens culinaris agglutinin (LCA) column.

Vicia villosa B4 lectin inhibits nucleotide pyrophosphatase activity toward UDP-GalNAc specifically

Plant seed lectins play a defense role against plant-eating animals. Here, GalNAc-specific Vicia villosa B4 lectin was found to inhibit hydrolysis of UDP-GalNAc by animal nucleotide pyrophosphatases, which are suggested to regulate local levels of nucleotide sugars in cells. Inhibition was marked at low concentrations of UDP-GalNAc, and was reversed largely by the addition of GalNAc to the reaction mixture. In contrast, lectin inhibited enzymatic hydrolysis of other nucleotide sugars, such as UDP-Gal and UDP-GlcNAc, only to a small extent, and GalNAc did not affect such an inhibition. The binding constant of the lectin for UDP-GalNAc was as high as 2.8 x 10(5) M-1 at 4 degrees C, whereas that for GalNAcalpha-1-phosphate was 1.3 x 10(5) M-1. These findings indicate that lectin inhibition of pyrophosphatase activity toward low concentrations of UDP-GalNAc arises mainly from competition between lectin and enzyme molecules for UDP-GalNAc. This type of inhibition was also observed to a lesser extent with GalNAc-specific Wistaria floribunda lectin, but not apparently with GalNAc-specific soybean or Dolichos biflorus lectin. Thus, V. villosa B4 lectin shows unique binding specificity for UDP-GalNAc and has the capacity to modulate UDP-GalNAc metabolism in animal cells.

Lectin affinity high-performance liquid chromatography: interactions of N-glycanase-released oligosaccharides with leukoagglutinating phytohemagglutinin, concanavalin A, Datura stramonium agglutinin, and Vicia villosa agglutinin

We have developed a lectin affinity high-performance liquid chromatography technique for analysis of oligosaccharides using columns of silica-bound lectins. Purified leukoagglutinating phytohemagglutinin (L-PHA), concanavalin A (Con A), Datura stramonium agglutinin (DSA), and Vicia villosa agglutinin (VVA) were covalently coupled to periodate-oxidized diol-silica by reductive amination. Homogeneous oligosaccharides of known structure, purified following release from Asn with N-glycanase and reduction with NaBH4, were tested for their ability to interact with the silica-bound lectins. The characteristic elution position obtained for each oligosaccharide was reproducible and correlated with specific structural features. The oligosaccharide specificities displayed by silica-bound L-PHA, Con A, and DSA were virtually identical to those established utilizing lectin-agarose conjugates. Analysis of oligosaccharides by lectin affinity HPLC allowed further definition of the specificity of VVA for N-glycanase-released, reduced oligosaccharides. Lectin affinity HPLC is rapid and convenient, providing an important structure-specific dimension to oligosaccharide analysis. This technique is particularly useful when utilized in conjunction with anion-exchange and ion-suppression amine adsorption HPLC methods, which fractionate on the basis of charge and size, respectively. In addition to their utility for oligosaccharide characterization, these affinity columns demonstrate the high degree of oligosaccharide specificity displayed by plant and animal lectins.